Effect of sintering temperature on density, microstructure, and depth hardness of stellite-6 produced by material extrusion (MEX)

Material Extrusion (MEX) offers an efficient and scalable route to near-net-shape parts while decoupling shape formation from densification. However, there is a distinct lack of systematic data regarding the sintering behavior and depth-resolved properties of MEX-processed Stellite-6, particularly when utilizing a fully thermal debinding route. This study quantifies how sintering temperature influences densification and the mechanical response of Stellite-6 fabricated by MEX with fully thermal debinding. Green bodies extruded from the filament were sintered at 1300, 1310, and 1320°C. Relative density, dimensional stability, microstructure, and through-thickness Vickers hardness (HV0.3) were evaluated. Density went up steadily with temperature as most of the interconnected pores closed and particle necks grew stronger. At 1320°C, however, microstructural heterogeneity increased and noticeable edge warpage compromised the dimensional stability of the printed parts. The 1310°C condition offered the best overall compromise, combining high densification and microstructural stability with a uniform hardness of ∼631 HV0.3. Selecting a sintering schedule centered at 1310°C therefore maximizes density while maintaining consistent microhardness across MEX-processed Stellite-6 components. Future perspectives include investigating the effects of isothermal hold duration and post-sintering hot isostatic pressing (HIP) to eliminate residual porosity and further enhance the mechanical performance.